1. Technical Field
The present disclosure relates to a semiconductor package and method of manufacturing the same, and, more particularly, to a bonding structure for a semiconductor package and method of manufacturing the same.
2. Description of the Related Art
In a known semiconductor flip-chip bonding process, a nickel layer is plated on a metal pillar of an upper chip to serve as a barrier layer, and then a solder is formed on the nickel layer. Next, the upper chip is placed on a lower chip or a substrate, where the solder on the metal pillar will contact a surface finish layer on a bonding pad of the lower chip or the substrate. Then, a reflow process is performed to melt the solder and to bond the metal pillar to the bonding pad, to form a flip-chip bonding structure.
In the known process, a large amount of solder is used in order to provide effective bonding between the metal pillar and the bonding pad. Since the outer diameter of the solder cannot be effectively decreased, a pitch between the metal pillars cannot be effectively reduced. In addition, to make the solder reach a molten state, the solder is heated to above 300° C. However, in such a high-temperature environment, the upper chip, the lower chip or the substrate is prone to warping, and the metal pillar is easily oxidized. To avoid oxidation of the metal pillar, another known technique is to perform high-temperature bonding in a vacuum environment. However, such a technique will increase the manufacturing cost, and cannot solve the warpage problem.
Moreover, to make the reflow process of the solder be carried out at a lower temperature, a solder is typically used with a reflux agent or an organic compound. Removal of such reflux agent or organic compound afterwards typically will raise environmental issues. Addressing these issues will incur additional cost.
Therefore, it is desirable to provide a semiconductor bonding structure and process that can solve the above problems.